As is known, electronic circuits are used in a variety of applications. One example application is in sensing applications where a circuit including one or more sensing elements (e.g., pressure sensing elements, temperature sensing elements, light sensing elements, acoustic sensing elements, and magnetic field sensing elements) is used to detect one or more parameters (e.g., pressure, temperature, light, sound, magnetic field). Magnetic field sensors, for example, are circuits including one or more magnetic field sensing elements, generally in combination with other circuit components (e.g., analog, digital and/or mixed signal components), and are used to detect a magnetic field.
In motion (e.g., rotation) detectors, for example, a magnetic field sensor may used to detect motion of an object, such as a ferromagnetic object, for example, a gear or ring magnet. A magnetic field associated with the object is typically detected by one or more magnetic field sensing elements, such as a Hall effect elements or a magnetoresistance elements (e.g., giant magnetoresistance (GMR) elements), which provide a signal (i.e., a magnetic field signal) proportional to a detected magnetic field. One example motion detector is described in U.S. Pat. No. 8,624,588 entitled “Apparatus and Method for Providing an Output Signal Indicative of a Speed of Rotation and a Direction of Rotation as a Ferromagnetic Object,” which is assigned to the assignee of the present disclosure and incorporated herein by reference in its entirety.
The magnetic field sensing elements and other circuitry may have different power requirements and, thus, may be powered by signals (e.g., voltage or current signals) of varying levels (e.g., voltage or current levels) as may be generated by one or more signal sources (e.g., voltage or current regulators). Some magnetic field sensor integrated circuits (ICs) contain signal regulation circuitry and methods to provide substantially fixed output signals (e.g., voltage or current signals) to power the magnetic field sensing elements and other circuit components.
In high precision applications such as automobiles, accuracy variations in the detected motion of a target object (e.g., resulting from irregularities in a sensed target profile of the target object) can be problematic. Engine ignition timing, for example, depends on consistent detection accuracy. As one example, when magnetic field sensing elements and other circuitry of a magnetic field sensor IC are not powered properly, for example, detection accuracy of the magnetic field sensor IC can be negatively impacted. Furthermore, in safety critical applications such as automobiles, compliance with standards such as Automotive Safety Integrity Level (ASIL) standards, generally require safety mechanisms to ensure proper circuit operation.